Synthetic textured yarn

ABSTRACT

AN IMPROVED SYNTHETIC TEXTURED YARN COMPOSED OF MORE THAN TWO KINDS OF THERMOPLASTIC SYNTHETIC FILAMENTS HAVING DIFFERENT FLEXURAL RIGIDITIES, TORSIONAL RIGIDITIES, FINENESS AND MIXING RATIOS. PARTICULAR DENFINITIONS IN THE RELATIONS AMONG THOSE FACTORS ASSURES REMARKABLY ENHANCED BULKINESS AND CRIMP RIGIDITY OF THE THE YARN COMPOSED OF THE FILA-   MENTS. DIFFERENCE IN THE CROSS SECTIONAL PROFILES OF THE COMPONENT FILAMENTS PROVIDES ADDITIONAL DEEP COLOUR EFFECTS TO THE TEXTILE FABRIC MADE OF THE TEXTURED YARN.

Feb. 9, 1971 osmo |ZUKA ETAL 3,561,207

I SYNTHETIC TEXTURED YARN Filed Aug. 16, 1968 7 Sheets-Sheet l B10650 as z 2% mo Emmi z 2 4 o FLEXUAL RIGIDITY IN m 5 m ,5 QmmO4m wQ mum waszmo m0 mmmfijz dyne-cm OF THE FILAMENT FLEXUAL RIGIDITY IN dyne-- :m OF A COMPO- NENT FILAMENT m y s o Zm QwmDkXmE.

uo a 7: M23? 028% Feb. 9,1971 yQ$H|Q [ZUKA EI'A L 3,561,207

SYNTHETIC TEXTURED YARN Filed Aug. 16, 1968 7 Sheets-Sheet 8 2b xlO' v FLEXUAL RIGIDITY IN dyne-cm 7F? HEEXE OF A COMPONENT FILAMENT CONTAINED O O O s m4 2 Zm ommprxmc. mo

. To 7: E92. EEO

TORSIONAL RIGIDITY IN d ecm' OF A COMPONENT FILAMENT Feb. 9, 1971 YQSHIQ IZUKA ETAL 3,561,207

SYN'JI'I'XEI'I'IC TEXTURED YARN 7 Sheets-Sheet 4 Filed Aug. 16, 1968 CRIMP RIGIDITY IN "/0 OF MATERIAL TEXTURED YARNS lb2b3b40506b mm mm 10.55% \eOm.

5 0 z M6552. mom 52381 .O z 23 G INII. VIAv M F O l m m G W V A. M

COMPONENT FILAMENT Feb. 9, 1971' YQSHIQ zu A ETAL v 3,561,207

- SYNTHETIC TEXTURED YARN Fil ed Aug. 15; 1968 Y 7 Sheets-Sheet 5 LOAD IN 9 REQUIRED FOR 50% STRETCH INCREASE IN OF ,CRIMP I v RIGIDITY 0F MATERIAL TEX- 'TURED YARNS DIFFERENCE- IN TOTAL EVALUATION OF PERSONAL HANDLING TEST 7 Sheets-Sheet 6 I 1971 vosl-uo IZUKA SYNTHETIC 'rnx'runmmm Filed Aug. 16, 1968 MIXING RATIO IN OF A COMPONENT FI LAMENT FINENESS IN denier OF A COMPONENT FILAMENT m m mw Feb. 9,1971 Yosmo .ZUKA ETAL 3,561,207

SYNTHETIC TEXTURED YARN Filed. Aug. 16; 1968 r Shets-Sheetfi AIR CONTENT IN /0 OF A PLIED 'TEXTURED YARN o @0 00 360400 5m. 0 NUMBER IN Turns/meter O Q OF THE SECONDARY TWISTS I Hg. /5 9 G DEGREE IN g rode OF I DEEP COLOUR EFFECT 5'0 160 7 60 2'00 DlFFERENCE IN MOLECULAR WEIGHT OF DYESTUFFS Int. Cl. D02g 3/04 U.S. Cl. 57140 6 Claims ABSTRACT OF THE DISCLOSURE An improved synthetic textured yarn composed of more than two kinds of thermoplastic synthetic filaments having different flexural rigidities, torsional rigidities, fineness and mixing ratios. Particular definitions in the relations among those factors assures remarkably enhanced bulkiness and crimp rigidity of the yarn composed of the filaments. Difference in the cross sectional profiles of the component filaments provides additional deep colour effects to the textile fabric made of the textured yarn.

The present invention relates to an improved synthetic textured yarn, more particularly relates to an improved synthetic textured yarn composed of more than two kinds of thermoplastic synthetic filaments having different flexural rigidities.

The term synthetic textured yarn hereinafter used refers to textured multifilament yarns composed of at least one of polyamide fibers, polyester fibers, polyolefin fibers and polyethylene fibers or to textured yarns composed of conjugate fibers containing different kinds of polymers in a concentric, eccentric or bi-metal arrangement.

Among the various types of synthetic textured yarns which are showing remarkable penetration into the field of textile materials recently, synthetic textured yarns composed of more than two kinds of synthetic thermoplastic filaments are well-known. However, such type of synthetic textured yarn has been used, in most cases, for the purpose of ornamental eflects. It is true, that, in some cases, they have been utilized for enhancing the functional properties of the yarn obtained but it resulted in only the combined development of the functional properties of the component fibers.

A principal object of the present invention is to provide an improved synthetic yarn composed of different kinds of thermoplastic synthetic filaments having remarkably improved appearance together with remarkably enhanced mechanical properties by defining the configurational features and the mechanical properties of the component filaments.

Another object of the present invention is to provide woven or knitted textile products having remarkably improved ornamental effects together with remarkably enhanced mechanical properties.

Further features and advantages of the present invention will be apparent from the ensuing description, reference being made to the accompanying drawings in which;

FIG. 1 is a graphical representation of the relation among the flexural rigidity of a component filament, the corresponding height and number of crimps developed on the filament by a crimping treatment,

United States Patent FIG. 2 is a graphical representation of the relation between the flexural rigidity of a component filament and the corresponding specific volume of a textured yarn composed of the filaments,

FIG. 3 is a graphical representation of the relation between the flexural rigidity of a component filament and the cirresponding specific volume of a textured yarn containing the filaments,

FIG. 4 is a graphical representation of the relation between the torsional rigidity of a component filament and the crimp rigidity of a textured yarn composed of the filaments,

FIG. 5 is a graphical representation of the relation between the torsional rigidity of a component filament and the evaluation of the personal handling test applied to a knitted fabric made of the textured yarns composed of the filaments,

FIG. 6 is a graphical representation of the relation between the torsional rigidity of a mixing component filament and the crimp rigidity of a tri-components textured yarn containing the filaments,

FIG. 7 is a graphical representation of the relation between the crimp rigidity of a tri-components textured yarn shown in FIG. 6 and the stretching force required for 50% stretch of a knitted fabric made of the textured yarns,

FIG. 8 is a graphical representation of the relation between the mixing ratio of a mixing component filament and the increase in crimp rigidity of a tri-components textured yarn containing the filaments with respect to that of a mono-component textured yarn,

FIG. 9 is a graphical representation of the relation between the increase in crimp rigidity of a textured yarn and the load required for 50% stretch of a knitted fabric made of the nylon D/2-2AF textured yarns,

FIG. 10 is a graphical representation of the relation between the mixing ratio of a component filament and the difference in total evaluation of a personal handling test of a knitted fabric made of a tri-components textured yarn containing the filaments,

FIG. 11 is a graphical representation of the relation between the fineness of the mixing component filament and the crimp rigidity of a tri-components textured yarn containing the filaments,

FIG. 12 is a graphical representation of the relation between the fineness of a componentfilament and the evaluation of the personal handling test applied to a knitted fabric made of tri-components textured yarns containing the filaments,

FIG. 13 is a graphical representation of the relation between the number of the secondary twists imparted to a plied textured yarn of the invention and the air content thereof,

FIG. 14 is a diagrammatic cross sectional view of a textured yarn according to the present invention containing two kinds of component filaments having different cross sectional profiles and finenesses,

FIG. 15 is a graphical representation of the relation between the difference in the molecular weights of dyestulfs used for dyeing a knitted fabric made of textured yarns shown in FIG. 14 and the degree of deep colour effects observed on the fabric.

As is generally known, bulkiness is an important factor for determining the functional quality of a textured yarn composed of thermoplastic synthetic filaments. As a result of our research, it was found that the bulkiness of this type of textured yarn is mainly dependent upon the number of crimps, dimensional characteristics of crimps, height of crimps and compressive strength of the individual filaments contained in the component yarns. Moreover, a further research revealed that the bulkiness of the textured yarn is dependent upon the combined effects of the above-described characteristic features of the individual filaments contained in the component yarns. In other words, the interaction of such individual characteristic features plays an important role in determining the bulkiness of the textured yarn obtained as is hereinafter explained in details.

Referring to FIG. 1, correlations among the number of crimps, the height of crimps and the flexural rigidity of the component filaments are shown.

In the drawing, the curve designated with a shows the relation between the flexural rigidity and the corresponding number of crimps while the curve designated with b shows the relation between the flexural rigidity and the corresponding height of crimps. The number of crimps was measured by cutting a crimped nylon yarn of 70 denier into a given length in a sufficiently free condition, dividing the yarn into indivdual component filament, fixing one end of the individual filament, loading a weight of 0.1 g./ denier to the other end of the filament, relaxing the filament at a relaxing ratio of 20% and counting the number of filaments in the relaxed condition. Together with the number of crimps, the height of crimps was also measured in same way. The value of the flexural rigidity is given by the following formula:

=EI (dyne-cm?) wherein E=Youngs modulus I=Moment of inertia of area As is apparent from the result shown in the drawing, a smaller flexural rigidity of fibers is accompanied by a lower height and a number of crimps of the filament while a larger flexural rigidity of the filament is accompanied by a higher height and a smaller number of crimps of the filament. In other words, the larger the flexural rigidity characteristic to the filament, the rougher is the appearance of the filament.

Referring to FIG. 2, the relation between the flexural rigidity of the component filaments and the specific volume of the yarns is shown. In the drawing, the value of the specific volume was measured in the following manner. A nylon yarn of 70 denier was thermally treated in a water bath of 60 C. for 20 minutes to develop crimps. However, in case polyester yarn is used as the specimen, it is necessary to use a water bath of 90 C. After the development of crimps, the yarn was loaded with a weight of mg./denier and the apparent diameter D of the yarn was measured. The value of the specific volume Vsp of the specimen yarn was calculated by:

1rD l 3 Vsp- (cm. lg.)

wherein D=Apparent diameter of the specimen yarn in cm. l=Length of the specimen yarn in cm. m=Mass of the specimen yarn in g.

The specific volume thus obtained is regarded as an important index for representing the degree of the bulkiness of a yarn.

By combining the result shown in FIG. 1 with that shown in FIG. 2, it is apparent that the height of crimps of the individual filament does not affect the value of the specific volume of the yarn composed of such filaments. Consequently, it is concluded that the bulkiness of a yarn is not dependent upon the height of the crimps of the individual filament composing the yarn. With respect to this fact, there seems to be a general misunderstanding that the bulkiness of a yarn is linearly related to the flexural rigidity of the individual filament composing the yarn. As is apparent from the results shown in FIGS. 1 and 2, a yarn composed of filaments having relatively large flexural rigidity is provided with relatively high crimps and these high crimps of the component filaments result in a relatively large apparent diameter and resistance against compression of the yarn composed of the filaments. However, as is shown in FIG. 1, such high crimps are accompanied by relatively small number of crimps, and this small number of crimps of the individual filament also cause easy approach of the adjoining filaments within the configuration of the yarn composed of the filaments. Consequently, when only filaments having relatively large flexural rigidity are used in the manufacture of a textured yarn, the textured yarn obtained cannot exhibit excellent bulkiness in spite of a relatively large flexural rigidity of the individual filament composing the yarn.

On the contrary, when only filaments having a relatively large flexural rigidity is used in the manufacture, the resulting situation is the opposite of the facts above-described. Moreover, it goes without saying that the large flexural rigidity of the component filaments results in effective maintenance of the bulkiness of the textured yarn composed of such filaments.

Now, it has become apparent that the bulkiness of a crimped textured yarn is dependent to a great extent upon the interaction between the two mutually inconsistent characteristic features of the filaments composing the yarn.

After repeated research, the inventors of the present invention have found that is possible to obtain a crimped textured yarn provided with excellent bulkiness effectively by making the yarn from at least two groups of component filaments having different fiexual rigidities, more particularly by defining the number of the filaments within the respective groups. The results of the experiments carried out by the inventors are graphically shown in FIG. 3, wherein the specific volume of the crimped textured yarn is taken on the ordinate while the flexural rigidity of the component filaments is taken on the abscissa. In the experiment, the crimped textured yarns used as specimens were prepared by mixing nylon crimped textured yarn with yarns composed of filaments having larger flexural rigidity at a given mixing ratio. The total denier of the textured yarn was 70. The flexural rigidity of the nylon 30 denier monofilament yarn was estimated to be about 1x10 dyne-cm. After mixing, the mixed yarn was subjected to a conventional false-twisting process, and the specific volume of the crimped textured yarn thus obtained was measured in the manner already described in detail. In the drawing, the curve designated with a corresponds to a mixing ratio of 8%, the curve b to 10%, the curve c to 20% and the curve d to 30%. The flexural rigidity of the component filaments ranges from 1 10- to 2O 10- dyne-cm.

As is apparent from FIG. 3, the specific volume of the textured yarn obtained cannot be increased without limit by increasing the mixing ratio of the component filaments containing fibers of relatively large flexural rigidity of over 10%. In other words, there is an upper limit to the increase in the specific volume of the textured yarn due to increase in the mixing ratio of the component yarn containing filaments of relatively large flexural rigidity. In case of the example shown in FIG. 3, the specific volume of the textured yarn obtained does not exceed 10 cm. g. by increasing the mixing ratio over 10%.

The following examples are illustrative of the result obtained from experiments by the inventors of the present invention.

EXAMPLE 1 A false-twisted yarn of the present invention of 100 denier was manufactured from by weight of nylon filaments having a flexural rigidity of 1.6 10- dyne-cm. and 20% by weight of nylon filaments having a flexural rigidity of 6.8 10 dyne-cmfi. The resulting specific volume of the yarn thus manufactured was 7.82 cmfi/g. For comparison, an ordinary false-twisted yarn of denier was manufactured from 100% of nylon filaments having a flexural rigidity of 1.6 10- dyne-cmF. The

resulting specific volume of the yarn thus prepared was 7.06 cm. g. As is apparent from those results, the specific volume ofthe yarn was increasedby 10.7% by the application of the theory of the present invention.

EXAMPLE 2 A false-twisted yarn of the present invention of 150 denier was manufactured from 50% by weight of polyester filaments having a flexural rigidity of 3.82 10 dyne-cmfi, 30% by weight of polyester filaments having a flexural rigidity of 6.25 10 dyne-cm. and 20% by weight of polyester filaments having a flexural rigidity of 18.3)(10 dyne-cm. The resulting specific volume of the yarn thus obtained was 12.43 cm. g. For comparison, an ordinary false-twisted yarn of 150 denier was manufactured from 100% of polyester filaments having a flexural rigidity of 3.82 ldyne-cmP. The resulting specific volume of the yarn thus obtained was 10.97 cm. /g. A comparison of both results indicates that a 13.3% increase in the specific volume of the false-twisted yarn obtained was attained by the application of the theory of the present invention.

From the results shown in FIG. 3 together with those of Examples 1 and 2, it is concluded that the object of the present invention can effectively be attained even when the upper limit of the larger flexural rigidity of the filament to be mixed does not exceed times the smaller flexural rigidity of the filament to be mixed.

Filaments having different flexural rigidities used in the present invention can be chosen from a group composed of filaments manufactured by the same process but having different fineness, filaments manufactured from polymer solutions having different viscosities, filaments manufactured at different drawing ratios in the spinning process, filaments manufactured from different kinds of raw material polymers, filaments manufactured from copolymers, filaments manufactured from raw material polymers of the same kind but having a slightly different chemical construction, filaments composed of fibers having different cross-sectional profiles and filaments composed of conjugate fiber containing polymers of different flexural rigidities in a concentric, eccentric or bi-metal arrangement.

Further, the manufacture of the bulky textured yarn utilizing the theory of the present invention can be carried out by any of the false-twisting method, the conventional twisting method (Italian throwing machine method), the stuffing box method, the gear crimping method, the postor pre-twisting method and the edge crimping method.

In the above-described embodiments of the present invention, a limitation has been proposed to the value of the flexural rigidities of the filaments composing the crimped textured yarn.

And it was further disclosed that, bymanufacturing a textured yarn from filaments having such individually limited flexural rigidities, the textured yarn obtained forms a fibrous assemblage composed of different types of filaments having various crimps of different numbers and heights. Such difference in dimensional features of the filaments composing the yarn results in formation of remarkable intervening spaces among the adjacent filaments to provide effective enhancement of the bulkiness of the yarn obtained.

Together with the problem of the flexural rigidities of the component filaments, it was further revealed, by the inventors of the present invention as the result of their repeated experiments, that the difference in the fineness of the component filaments also plays an important role in the enhancement of the bulkiness of the crimped textured yarns composing of the filaments.

As is repeatedly stated in the foregoing description, difference in the dimensional features of the crimps developed on the individual component filaments is caused by limiting the flexural rigidities of the component filaments. However, it will be well understood by ones 6 skilled in the art that such difference in the dimensional features of the crimps can also be caused by making the fineness of the component filaments different. Consequently, the same kind of effect can be obtained in both cases.

It is experimentally known that the finer the synthetic filament, the smaller is the number and the larger the height of crimps which can be developed on the filament. Therefore, it is assumed that a close correlation exists between the fineness and the flexural rigidities of the filament composing the textured yarn. As the result of our experiment carried out emphasis placed on this point, it was confirmed that a crimped textured yarn having a remarkably improved 'bulkiness can be manufactured by composing a multifilament yarn having a mean fineness ranging between 2.5 and 3.5 denier from 60 to 40% by weight of filaments of smaller denier and 40 to 60% by weight of filaments having a fineness larger than that of the filaments of the smaller denier by from 2 to 5 denier, imparting twists into the multifilament yarn, heat setting the twisted yarn and untwisting the heat set yarn more over, further texturing method can be used. It was further confirmed that a fabric having improved bulkiness, excellent elastic property and tensile property can be obtained by heat setting the crimps of the crimped textured yarn and then weaving this. The same kind of result can be obtained by utilizing the conventional stuffing box method in the crimping process as is shown in the following Example 4.

EXAMPLE 3 A crimped textured yarn was prepared by composing a polyester multifilament yarn of 150 denier from 36 polyester filament of 2 denier and 12 polyester filament of 6 denier, subjecting the multifilament yarn to the conventional twisting-heat setting-untwisting process and heat setting the crimped yarn in a wet condition. A blended yarn of 40 /2 composed of 65% by weight of polyester fibers and 35% by weight of rayon fibers was also prepared. A basket weave fabric having a warp density of 96 ends/inch and a filling density of 94 picks/inch was woven using the blended yarn as the warp and the crimped textured yarn as the filling. For the purpose of comparison, a fabric of the same design and construction was also prepared using the blended yarn as the Warp and the crimped textured yarn as the filling. In this case, however, the crimped textured yarn was composed of only polyester filaments of 2 denier. The functional properties of the sample fabrics thus prepared are illustrated in Table 1. Items shown in the table are measured and calculated in the following manner.

(1) Relative thickness ratio wherein B=Thickness in mm. of the standard sample A=Thickness in mm. of the test sample (2) Fabric stretch A sample fabric with length of 20 cm. in the stretching and width of 2.5 cm. was clamped between a pair of clamps with an effective clamping distance of 10 cm. The length of the clamping distance (A) was measured under an original load of 50 g. Next a load of 1,000 g. was applied to the sample and the length of the clamping distance (B) was measured in the loaded condition. The resulting fabric stretch in percent is given by;

BA XIOO (3) Compressional resilience A sample fabric having a dimension of x 5 cm. was tested on a compressometer. The thickness (A) of the sample was measured under an original load of 5 g./cm. Next, a load of 240 g./cm. was applied to the sample and the thickness (B) of the sample was measured. After removing the load for 1 minute, a load of 5 g./cm. was applied again to the sample and the thickness (C) of the sample was measured in the loaded condition.

Then, the compressional resilience is given by;

(4) Prompt fabric recovery The sample fabric was stretched to 5% at a stretching rate of 20 cm./ min. on a tensilon tester. After the stretch has been removed, the strain of the fabric recovered instantly after the removal of the stretch was measured. The prompt fabric recovery in percent is given by;

B XIOO wherein B=Recovered strain after removal of stretch A=Total strain due to stretch (5) Flexural rigidity A sample fabric having a dimension of 1.7 cm. in length and 0.6 cm. in width was tested on a fabric handling tester of the vibration type. The length of the sample disposed to a vibrating member of the tester was measured. By-vibrating the sample on the tester, the resonant frequency of the sample was recorded, and the flexural rigidity of the samples was calculated by A=Linear density of the sample I=Length of the sample f=Resonant frequency of the sample (6) Drawing-out resistance wherein =Fullness of the sample A=Area of the smallest rounded portion of the sample t=Thickness of the sample A ring was lowered through the sample and the amount of the force required was recorded and the drawing-out resistance in g. was given by;

Recorded value Measured fullness As it is apparent from the results shown in the table, the fabric containing the textured yarns of the present invention is provided with improved functional properties.

EXAMPLE 4 A crimped textured yarn was prepared from a polyester multifilament yarn of 150 denier composed of 30 polyester filaments of 2 denier, 15 polyester filaments of 4 denier and 5 polyester filaments of 6 denier, this multifilament yarn was subjected to the conventional crimping process of stufiing-box type and the crimped yarn 'was heat set in a wet condition. A plain weave fabric having a warp density of ends/ inch and filling density of 84 picks/ inch was woven using the above-described crimped textured yarns. For the purpose of comparison, a fabric of the same design and construction was also prepared using the crimpel textured yarns composed of only polyester filaments of 2 denier. The functional properties of the sample fabrics thus prepared are illustrated in Table 2 wherein the measurements were made in the same way as in Example 1.

As is apparent from the results shown in the table, the fabric containing the textured yarns of the present invention is provided with improved functional properties when compared with the fabric made of the conventional textured yarns.

Together with the limitation required for the fiexural rigidities of the filament composing the textured yarn of the present invention, it was further revealed that the functional properties of the textured yarn can effectively be improved by placing a limitation to the torsional rigidities of the filaments composing the textured yarn. It is assumed that a relatively large torsional rigidity of a filament is accompanied by increased crimp rigidity of the filament. However, it is further accompanied by a roughened touch of the filament. Here, the value of the torsional rigidity is given by the following formula;

G] (dyne-cm?) wherein G=Shear modulus J =Polar moment of inertia of area Referring to FIG. 4 a relation between the crimp rigidity and the torsional rigidity of a nylon crimped textured yarn is shown graphically. In the present case, the crimped textured yarn was manufactured from a nylon multifilament yarn of denier by the conventional twistingheat setting-untwisting method. As is apparent from the result shown in the drawing, the crimp rigidity of the textured yarn manufactured increases as the torsional rigidity of the component filaments increases. Using this nylon textured yarn, a knitted fabric of plain knitting (14 gauge) having a weight of 110 g./m. was prepared,

and the knitted fabric was subjected to a personal handling test.

The result of the handling test is shown in FIG. 5, wherein the evaluation by the examiners ranging from to 50 is taken on the ordinate and the torsional rigidity of the filament used as the material of the knitted fabric is taken on the abscissa. As is apparent from the result shown in the drawing, rough handling of the knitted fabric is remarkably increased when the torsional rigidity of the material filaments exceeds 0.1 dyne-cm.

Referring to FIG. 6-, the relations between the crimp rigidity of a nylon crimped textured yarn of 100 denier containing nylon filaments having a torsional rigidity of 1.04 l0- dyne-cm. and the torsional rigidity of the filaments mixed with the above-described nylon filament are shown. In the drawing, the curve designated with 01 corresponds to the textured yarn containing a single mixing filament, the curve 12 to two mixing filaments, the curve 0 to three mixing filaments and the plot d to no mixing filaments. Each curve was obtained by connecting the measured results obtained in the form of repeated average. By applying the method of statistical analysis to the results obtained, it was confirmed that no significant difference in the crimp rigidity of the textured yarn manufactured can be observed unless the torsional rigidity of the mixing filament is larger than that of the filament to be mixed by at least five times. In other words, the resulting crimp rigidity of the textured yarn obtained can be remarkably enhanced when the torsional rigidity of one of the component filaments is larger than that of another of the component filaments by at least five times. This conclusion can also be applied to a textured yarn containing more than three component filaments having different torsional rigidities. In this case, the same relation is required between the component filament having the largest torsional rigidity and the remaining component filaments.

Considering from the results shown in FIGS. and 6, the torsional rigidity of the filaments composing the textured yarn should preferably be smaller than 0.5 dynec'm. and the mixing ratio of the component filaments having a relatively large torsional rigidity should also preferably be smaller than 50% by weight of the textured yarn manufactured.

A knitted fabric of plain knitting (14 gauge) having a weight of 12 5 g./m. was prepared using the abovedescribed textured yarn, and the stretching force required for stretching a sample of 2.5 cm. in width made of the above-described knitted fabric at a stretching ratio of 50% was measured.

The results obtained are shown in FIG. 7, wherein the stretching force in g. required is taken on the ordinate and the crimp rigidity in percent of the material textured yarn is taken on the abscissa. It will be well understood from the results shown in FIG. 7 that not only the bulkiness but also the crimp rigidity of the textured yarn can be effectively improved by placing a limitation to the torsional rigidity of the component filaments as is already described. For the purpose of the present invention, it is also possible to utilize conjugate fibers containing components of different torsional rigidities.

EXAMPLE 5 A nylon crimped textured yarn of 70 denier was manufactured by the conventional false-twisting method from 10 nylon filaments having a torsional rigidity of l.23 10" dyne-cm. and 2 nylonfilaments having a torsional rigidity of 35.20 10 dyne-cmF. The resulting crimp rigidity of the textured yarn was 54.2%. For the purpose of comparison, a nylon crimped yarn of 70 denier composed of only 24 nylon filaments having a torsional rigidity of 1.23 10 dyne-cm. was also manufactured in the same manner, and the resulting crimp rigidity of the textured yarn was 34.2%. A comparison of these two results indicates that there was an increase of 58.4% in the crimp rigidity of the textured yarn by mixing only 2 filaments having a larger torsional rigidity according to the present invention.

EXAMPLE 6 A polyester crimped textured yarn of 150 denier was manufactured by the conventional false-twisting method from 48 polyester filaments having a torsional rigidity of 274x10 dyne-cm. and 8 polyester filaments having a torsional rigidity of l.47 l0 dyne-c-mfi. The resulting crimp rigidity of the textured yarn was 45.3%. For comparison, a polyester crimped textured yarn of 150 denier composed of only 60 polyester filaments having a torsional rigidity of 2.74 10- dyne-cm. was also manufactured in the same manner, and the resulting crimp rigidity of the textured yarn was 36.9%. A comparison of these two results indicates that there was an increase of 22.8% in the crimp rigidity of the textured yarn by mixing only 8 filaments having a larger torsional rigidity according to the present invention.

It has become apparent, from the results shown in the foregoing examples, that a remarkable increase in the crimp rigidity of the textured yarn manufactured can be effectively obtained by mixing filaments having a torsional rigidity from 5 to 300x10" dyne-cm. with ordinary filaments having a torsional rigidity from 0.5 to 50X 10* dyne-cm.

Generally, a wide utilization of synthetic textured yarns in the field of woven or knitted fabrics depends on their bulkiness, tensile properties and characteristic hand. In accordance with this fact, the present invention provides synthetic textured yarns having improved bulkiness, tensile properties and favourable hand 'by defining the value of the flexural rigidities, the torsional rigidities and by placing limitation in the fineness of the individual filament composing the yarn. It is true that a synthetic crimped textured yarn composed of two kinds of filaments having different fineness is already known but such conventional textured yarn is accompanied with problems concerning the degree of difference in the fineness of the component filaments. Too large difference in the fineness of the component filaments often causes rough handling of the textile products made of the filaments while too small difference in the fineness of the component filaments is generally accompanied with small difference in the torsional rigidities and the number of crimps thereof and causes relatively low bulkiness of the textile products made of the filaments. Therefore, it can be well understood that it is necessary to place a limitation on the fineness of the component filament in order to attain the object of the invention.

However, in case more than three kinds of component filaments having different fineness are used in the manufacture of a textured yarn, it becomes possible to select component filaments having relatively large difference in the fineness between each other. Thus, this type of textured yarn conforms with the objects of the present invention very well.

.An experimental procedure for obtaining the limitation in fineness of the component filaments preferred for the manufacture of the textured yarn of the present invention is as hereinafter described.

Various types of nylon 6 textured yarns (hereinafter called tri-component textured yarns) of D/2 were prepared from nylon 6 filaments of 2.5 denier, 5 denier and 10 denier. For the purpose of comparison, a nylon 6 textured yarn (hereinafter called a mono-component textured yarn) of the same fineness composed of only nylon 6 filaments of 2.5 denier was also prepared. The crimp 1 1 rigidities of the respective textured yarns were measured and the percent increase in the crimp rigidity of the tricomponents textured yarn with respect to that of the mono-component textured yarn was calculated. Referring to FIG. 8, the relations between the above-described percent increase in the crimp rigidity and the mixing ratio of the component filaments of 5 denier with respect to the quantity of the component filaments of 2.5 denier and relations between percent increase of the crimp rigidity and the mixing ratios of the component filaments of 10 denier with respect to the quantity of the component filaments of 2.5 denier and 5 denier in the textured yarn are shown. In the drawing, the curve designated with a corresponds to mixing ratio of the filament of 10 denier, the curve b to 10% mixing ratio, the curve c to 30% mixing ratio, the curve d to 50% mixing ratio and the curve e to 70% mixing ratio. The crimp rigidity and the percent increase in the tensile recovery of the textured yarns are measured and calculated in the following manner.

(1) Crimp rigidity Crimp rigidity of a crimped yarn represents a recoverableness of crimps of the crimped yarn and has a close correlation with the fiexible properties and tensile properties of a textile product made of the crimped yarns. Moreover, in case crimped yarns are used in a pebbling fabric, crimp rigidity of the crimped yarn is closely correlated with a pebbling property of the fabric. Thus, the concept of crimp rigidity of a crimped yarn is often em ployed in the estimation of the resulting functional properties of a textile product of the yarn. It is known that the value of crimp rigidity is dependent upon such factors as the number of the crimps, the periodical pitch of the crimps, the dimensions of the crimps, Youngs Modulus, the torsional rigidity, the moment of inertia of area, and the polar moment of inertia of the crimped yarn.

A skein of the textured yarn of 10 winds was thermally treated in a hot water bath for 20 minutes in a relaxed condition. The temperature of the bath was maintained at 60 C. in case of nylon fibers or other fibers and 90 C. in case of polyester fibers. After the mentioned thermal treatment, the skein was dried at a room temperature for about 24 hours. Immersing the skein into a water bath maintained at about 20 C., a weight of 0.002 g./denier+0.1 g./denier was loaded to a skein in the bath for 2 minutes. After taking the skein out of the bath, the length of the wet skein under the mentioned loaded condition was measured. Immediately after this measurement a weight of 0.1 g./ denier was unloaded, the skein still in a wet condition was left for another 2 minutes with a loading of 0.002 g./ denier and, after this 2 minute interval, the length (1 of the skein under the mentioned loaded condition was also measured. In order to obtain the average, measurements were repeated 5 times, and the crimp rigidity in percent of the textured yarn specimen was given by;

(2) Percent increase in the crimp rigidity Increase in percent of the crimp rigidity is given by;

CO X100 wherein C =Crimp rigidity of the mono-component textured yarn. C =Crimp rigidity of the tri-components textured yarn.

12 For further discussion, a piece-dyed knitted fabric of circular interlocked rib knitting of 260 g./m. (24 gauge) was made of nylon textured yarns of 100 D/ 2 containing 24 filaments of similar fineness. The percent increase in the crimp rigidity of the material textured yarn and the load required for a 50% stretch of the sample knitted fabric having a width of 2.5 cm. was measured. Stretch was applied to the sample in the direction of lengthwise. Referring to FIG. 9, the relation between the percent increase in the crimp rigidity of the material textured yarn and the above-described load is shown. In this respect, the larger the load required for stretching, the larger is the resistance of the specimen fabric against stretch. Judging from the results shown in FIG. 9, the resistance of the specimen fabric against stretch is remarkably enhanced when the crimp rigidity of the material textured yarn exceeds 20%. From the results shown in FIG. 8, more than 20% increase in the crimp rigidity of the material textured yarn is obtained in case of the tricomponents textured yarn when the mixing ratio of one of the three component filaments contained in the textured yarn is at least larger than 10%. This is mathematically given by;

rn r/m wherein D =Total fineness in denier of the tri-components to textured yarn.

D Fineness in denier of one of the tri-components filaments.

A piece-dyed knitted fabric of interlocked rib knitting was made of the tri-components textured yarns shown in FIG. 8 and, for the purpose of comparison, a same type of knitted fabric was also made of the nylon 6 monocomponent textured yarns of 100 D/ 2. Both fabric samples were subjected to a personal handling test and the results of the test are shown in FIG. 10. Here, the personal handling test was carried out in the following manner.

The specimen fabric was subjected to a handling test by 10 examiners and each examiner recorded the results of his evaluation. Evaluation was indicated by integers ranging from 1 to 10. The difference of the total evaluations by the 10 examiners on the specimen fabric made of the monocomponent textured yarns and those on the specimen fabric made of tri-components textured yarns was calculated. The above-described evaluations were obtained as the result of combined appreciation of the specimen fabric by the examiners taking compressibility, touch, stretch, recovery from stretch, surface touch and compactness of the fabric into consideration. In the drawing, the difference of the total evaluation is taken on the ordinate and the mixing ratio in percent of the component filaments of 5 denier with respect to the quantity of the component filaments of 2.5 denier in the textured yarn is taken on the abscissa. The curve designated with a corresponds to 0% mixing ratio of the component filaments of 10 denier with respect to the quantity of the component filament of 2.5 denier, the curve b to 10%, the curve c to 30%, the curve d to 50% and the curve e to respectively.

As is apparent from the results shown in FIG. 10, the total evaluation of the specimen fabric composed of tricomponents textured yarn decreases considerably when the mixing ratio of one of the component filaments exceeds 50%, and a further increase in the mixing ratio of the component filament results in lowering on the handling test evaluation. Therefore it can be concluded, from the results of the above-described personal handling test, that the mixing ratio of one of the component filaments contained in a tri-components textured yarn should be smaller than 50%. This is mathematically expressed by;

yin T11 wherein D =Ttal fineness in denier of the tri-components textured yarn. D =Fineness in denier of one of the tri-components remarkable increase and the evaluation in the personal handling test is remarkably improved when the fineness of the mixing filament exceeds 3 denier. From the abovedescribed facts, it can be well understood that the following relation is required between the number of the mixing filaments.

I filaments (E and the total fineness (D 1n denier h Foflhhla 1 With Formula the followof the mixing filaments for obtaining a textured yarn lhg relatloh 1S Iequlfed hetWBeh the fineness Mn) of provided with desirable functional properties. one of the component filaments and the total fineness D (D of the textured yarn composed of those filaments 3; for obtaining an enhanced crimp rigidity of the yarn M: ggg quality of a kmtted fabnc made of the Here, (D /F is equal to the fineness of the individual mixing filaments.

0'1DT"=DM=0'5DTI1 (3) From the above dlscusslon, it can be concluded that, It was further confirmed by our experiments that the for the manufacture of a synthetic textured yarn having above-described relation is also applicable to synthetic improved bulkiness, crimp rigidity and handlingfrom textured yarns composed of more than four kinds of more than three kinds of thermoplastic material filaments, component filaments having different fineness. the relations defined by Formulas 3 and 4 must exist For the purpose of confirmation of the above deamong fineness, number and total fineness of one of the scribed fact, a nylon textured yarn of 70 D/2 was 'manucomponent filaments. In this respect, one of the comfactured by mixing nylon 6 component filaments having ponent filaments is regarded as being of largest fineness various fineness with a mixed bundle of another two among the filaments composing the textured yarn. components filaments of different fineness. The mean EXAMPLE 7 fineness of the component filaments contalned within the mixed bundle was 2.8 and 3.6 denier, and the mixing As 18 Shown i Table fOllr klnds of mono-C mp ratio of the mixing component filaments was 25% by multf-fi amerrt yarns for comparison, a bi-components weight of the mixed bundle of filaments. The relation be- Inultlfilament ya n, three klIldS of trl-components mult tween the fineness 0f the mixing component filaments and fi m t yarn of the Invention and tetra-components multithe crimp rigidity of the textured yarn obtained is shown filament yarns of the invention were prepared, respectlvein FIG. 11, wherein the curve designated with a corycase multlfilament y of the present responds to the mean fineness of 3.6 denier and the curve Vehtloh, the mlXmg ffltlo 0f the po e t fi aments wl b to 2.8 denier. Using the nylon textured yarn of 70 D/2 respect to the quant ty of the component filaments havused in the experiment shown in FIG. 7, a knitted fabric ing largest fineness with larger than 10% and the fiexural of interlo k knitting of 260 g (24 gauge) wa prerigidities of the former was smaller than 10 times of -pared and subjected to a personal handling test in the that of the latter. After the crimping operation, the charmanner already described. The results obtained are shown acteristic features of the textured yarns obtained were in FIG. 12, wherein the curve designated with a correcorded. Next, woven or knitted fabrics were made resopnds to a mean fineness of 3.6 denier and the curve from the textured yarns and the characteristic features b to 2.8 denier. 40 of the fabric obtained were also recorded. The result- It is apparent from the results shown in FIGS. 11 and ing characteristic features thus recorded are shown in 12 that the crimp rigidity of the textured yarn shows a Table 4.

TABLE 3 Detailed construction of the multi- Total filament M 1 N h t id M m doimanufaeturin 11 e O ii filiir fi ih m i e h s Niim ii er) textured yarn g Construction of the woven or knitted fabric 2 24) 1-al. Polyester (150-44)...[(5 0 {1 2 False-twisting Modified twill weave (used for warp and filling).

(58 5i 1-b do (150-44)..- 150-40 ..do Do.

(40-17 plus (20-5) 2-a Nylon6 (1l030) {(3(plg)s xstuffing box method Single ersey piece dyeing.

plus 20-2 2-b do (-30)- 110-30) do D0. 3-a Nylonfi (7015)... {(2h ih lFalse-twisting method Double jersey piece dyeing.

Oil- 1 a-b "do (70-15)..-- (70-15) do Do.

(40-13 c 3 .d0 (7015) plus }....de Do. (30-2) (50-24) 4-a Polyester conjugated (-48).-- (581 1 2) Thermal treatment at 150 0..-. Modified twill weave (used for warp and filling).

(58- 1 5) 4-1) do (150-48) (150-48) do Do.

1 Sufiix a represents the sample fabric of the present invention while I: and c are sample fabrics made of the conventional yarns for comparison.

2 The textured yarn was used in the form of a plied yarn.

TABLE 4 Characteristics Characteristic features of the fabric made of the texfeatures of tured yarns the textured yarn Evaluation of the personal handling Bulki- Crimp test ness rigidity Weight Thick- Stretch Sample in in in ness in Stifi- Crisp- Number cmfi/g. percent gJm. in mm. percent Touch ness ness It is apparent from the results shown in the tables that all the textured yarns of the present invention are provided with enhanced bulkiness compared with the conventional textured yarns. Furthermore, the sample fabric No. 3-a is also provided with a remarkably improved stretching ability.

Together with improvement in the bulkiness, the plied textured yarn of the present invention has a remarkably improved air containability that could hardly be found in any of the conventional plied textured yarns. Therefore, the elastic fabric made of the plied textured yarns of the present invention is improved with the best drape and handling quality when compared with the conventional ones.

Referring to FIG. 13, a relation between the percent air content of the plied textured yarn and the number of the secondary twists is shown. In the drawing, the curve designated with a corresponds to a plied textured yarn of the present invention made by doubling a textured yarn of sample No. 1-a with that of sample No. 1-b in Table 3 while the curve designated with b corresponds to a conventional plied textured yarn. As is apparent from the drawing, the plied textured yarn of the invention can maintain an air content larger than 100% unless the number of the secondary twists goes beyond 300 turns/meter while the air content of the conventional plied textured yarn becomes less than 100% if the number of the secondary twists exceeds 200 turns/ meter. Thus, the plied textured yarn of the present invention is provided with by far the best air containability when compared with the conventional plied textured yarn, especially in the area of relatively large number of secondary twists imparted into the doubled yarn.

The above-described air containability was measured and calculated in the following manner. A weight of 1 mg./denier was loaded to a single multifilament and the apparent diameter (A) of the filament was measured by using a photographic projector of 100 magnifications. Next, the actual diameter (B) of the filament was also obtained by considering the filament as a monofilament. Then, the percent air content of a textured yarn made of the filaments is given by;

Thus, the air content of the yarn represents the degree of space existing among the individual filaments composing the yarn and, consequently, is regarded as a measure of the bulkiness of the yarn.

It was further confirmed by the inventors of the present invention that a crape fabric having far improved quality can be manufactured by a simple method by composing the material multi-component textured yarn from filaments of different fineness wherein the thermal shrinkage of the component filaments of larger fineness is from 2 to 3% larger than that of the component filaments of smaller fineness. The crape fabric made of the conventional textured yarn was manufactured by sizing the material textured yarn, weaving the fabric while the crimps of the yarn are set by the sizing materials bestowed to the yarn and desizing the fabric by a finishing treatment subsequent to weaving, thereby developing inherent crimps of the yarn and pebbles of the fabric. In case the textured yarn of the present invention is utilized, manufacture of the crape fabric can be performed without the sizing operation. The results of our experiment proves that, for the production of a crape fabric having sufliciently developed pebbles, the thermal shrinkage of the component filaments of larger fineness is required to be from 2 to 3% larger than that of the component filaments of smaller fineness and, moreover, the relations defined by Formulas 2 and 3 must exist among the component filaments. In this case, the component filaments which are finer tend to be positioned near the central portion of the cross section of the textured yarn and the peripheral skin portion of the yarn is occupied by component filaments which are less finer. The characteristic configurational feature of the yarn provides a relatively soft touch of the fabric made of the textured yarns of the present invention.

It was further confirmed that the fineness of the component filaments which are finer should preferably be about three times larger than that of the component filaments which are less finer. By immersing the fabric made of such textured yarns into a hot water bath, the component filaments which are finer shows greater thermal shrinkage, resulting in the production of a crape fabric having suflicient degree of pebbles and remarkably en- H hanced resistance against compression as compared with the crape fabric made of the conventional textured yarns.

EXAMPLE 8 A polyamide multifilament yarn of 50 denier was twisted at a twisting rate of 300 turns/meter. A polyamide multifilament yarn of 50 denier, which was composed of 20 filaments of 2 denier having a thermal shrinkage of 11.8% and 1 filament of 10 denier having a thermal shrinkage of 14.5%, was subjected to the conventional twisting-heat setting-untwisting process to form a textured yarn. A plain weave fabric having a warp density of 145 ends/inch and filling density of 98 picks/ inch (both after finishing) was woven using the polyamide multifilament yarn as the warp and the polyamide textured yarn as the filling. Next, the fabric was treated with hot water to develop a 5.6% contraction. Then the crape fabric obtained was provided with pebbles having 10% more height and 10% shorter pitch as compared with a crape fabric manufactured by the conventional method including sizing of the material yarns.

EXAMPLE 9 A polyester multifilament yarn of 50 denier was twisted at a twisting rate of 100 turns/meter. A polyester multifilament yarn, which was composed of 16 filaments of 2 denier having a thermal shrinkage of 12.7% and 3 filaments of 6 denier having a thermal shrinkage of 15.0%, was subjected to the conventional twisting-heat settinguntwisting process to form a textured yarn. A plain weave -fabric having a warp density of 140 ends/inch and a TABLE Sample Fabric manufactured by the Fabric according to conventhe present invention tional method,

Filling No filling filling Item yarn sizing yarn sizing yarn sizing Height in mm. of the pebble 0. 076 0. 058 0.060 Pitch in mm. of the pebble 0. 084 0. 093 0. 092 Pebbling contraction in percenta 38 31 32 Stiffness in mm 65 62 56 Resistance against compression- 1 Excellent. 2 Ordinary.

Measurements in the table were made in the following method.

(1) Pebbling contraction Pebbling contraction is regarded as a contraction of the sample fabric due to development of pebbles and given by;

XIOO wherein A=Effective reed space of the loom used for weaving the fabric. B=Width of the fabric after finishing or dyeing.

(2) Stiffness in mm.

A sample fabric 2 cm. wide and 15 cm. long was tested on a Clark stiffness tester. When the reading of the sum of angles on both angle indicaters becomes 90:2, the length of the sample fabric was recorded as the stiffness in mm.

(3) Stiffness against compression The sample fabric was subjected to a personal handling test and the degree of resistance against gripping by hand was appreciated as a measure of resistance against compression.

It has been well known that a preferable luminous effect on a textile fabric can be obtained by using filaments having irregular cross sectional profiles such as triangular or rectangular as the material of the fabric. However, such application of filaments having irregular cross sectional profiles can not always assure sufficient luminous effect on the textile fabric because of relatively transparent appearance of the material synthetic filaments. Moreover, application of such material filament is often accompanied with relatively hard touch and cool feeling of the textile fabric which are generally not preferable for use in garments, etc. Therefore, the utilization of filaments having irregular cross sectional profiles in the field of textile fabric has been limited to a relatively narrow range.

Referring to FIG. 14, a cross section of a textured yarn manufactured according to the present invention is shown. This textured yarn, which comprises component filaments of larger fineness having a circular cross section and component filaments which are less finer having a cross section of irregular profile according to relations defined by Formulas 2 and 3, was processed by the conventional twisting-heat setting-untwisting operation. As is apparent in the drawing, component filaments of circular cross section are located near the central portion of the crosssection of the yarn and component filaments of irregular cross section are located in the periphery of the yarn. This characteristic disposition of the component filaments presents an outstandingly elegant luster together with improved soft touch of the textured yarn while eliminating drawbacks found in the conventional textured yarns. Our experimental results further revealed that such combined luminous and functional effects can be obtained when more than 4 denier difference exists in the fineness of the filaments composing the yarn. During dyeing the yarn, the dye affinity of the filaments of circular cross section, which are located in the central portion of the yarn, is greater than that of the filaments of irregular cross section, which are located in the periphery of the yarn. Therefore, remarkably improved luminous and colour effects on the fabric can be obtained by dyeing the fabric composed of textured yarn of the above-described type. This fact is proved by the following examples.

EXAMPLE 10 A nylon multifilament yarn, which is composed of 24 nylon filaments of 2 denier having a triangular crosssection and 2 nylon filaments of 25 denier having a circular cross section, was processed by the conventional twisting-heat setting untwisting operation to form a nylon textured yarn. A jersey fabric of double interlock rib knitting having a Weight of 280 g./m. (24 gauge) was manufactured using the textured yarns thus obtained. Next, the jersey fabric was dyed with a dyeing solution containing CI Direct Blue 171 and CI Acid Red 66. The dyed fabric obtained was provided with a remarkably improved fluorescent color effect of violet tone with excellent bulkiness and soft touch.

EXAMPLE 11 A nylon multifilament yarn, which is composed of 6 nylon filaments of 3 dinier having a rectangular cross section, 2 nylon filaments of 10 denier having a triangular cross section and one nylon filament of 30 denier having a circular cross section, was processed by the conventional false-twisting operation to form a nylon textured yarn. A jersey fabric of double interlock rib knitting having a Weight of 250 g./m. (22 gauge) was manufactured using the textured yarns obtained. Next, the jersey fabric was subjected to continuous treatment consists of scouring in relaxed condition, steam-setting and dyeing with a dyeing solution containing CI Acid Red 52. The dyed jersey fabric thus obtained was provided with outstandingly excellent luminous effects as compared with that made of the conventional textured yarns.

It was further made clear by our experiments that the above-described deep color effect observed on the textile fabric made of the textured yarns of the present invention can be effectively obtained by dyeing the fabric with a dyeing solution containing more than two kinds of dyestuffs whose molecular weights differ from each other by more than 100. By using this kind of dyeing solution a remarkably difference in the dye afiinities of the component filaments can be effectively obtained, thus resulting in development of elegant deep colour effect on the fabric.

Referring to FIG. 15, the relation between the difference in molecular weight of the dye stuffs used and the degree of the deep colour effect is shown. The evaluation of the degree of the deep colour effects is carried out in the following manner. After dyeing, the sample fabric of the present invention was exposed to a personal visible test by 20 examiners. In the drawing, grade 5 corresponds to a sample fabric whose deep colour effect was evaluated by from 18 to 20 examiners as being better than that of the fabric made of the conventional textured yarns, grade 4 corresponds to from 14 to 17 examiners, grade 3 corresponds to from 10. to 13 examiners, grade 2 corresponds to from 6 to 9 examiners and grade 1 corresponds to fewer than examiners.

EXAMPLE 12 A nylon textured yarn, which contains nylon filaments of 4 denier and 2 nylon filaments of denier, was manufactured by the conventional false-twisting method. In the configuration of the yarn obtained, the two filaments of 15 denier were located in the central portion of the cross section of the yarn and were surrounded by the 10 filaments of 4 denier. A plain weave fabric made of the textured yarns thus prepared and having a warp density of 90 ends/inch and a filling density of 80 picks/inch was dyed with a dyeing solution containing CI Acid Blue-120 (C H N O S Na and CI Acid Blue-25 (C H N O SNa). Then, the filaments located in the central portion of the yarn were dyed with CI Acid Blue-120 while the filaments located in the periphery of the yarn were dyed with Cl Acid Blue-25. The resulting dyed fabric was provided with outstandingly excellent and elegant deep colour effects evaluated as grade 5 as compared with dyed fabric of same construction made of the conventional textured yarns.

While the invention has been described in conjunction with certain embodiments thereof, it is to be understood that various modifications and changes may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. An improved multifilamentary synthetic textured yarn comprising: two or more kinds of thermoplastic synthetic filaments each having a different flexural rigidity, wherein the filaments having the largest flexural rigidity are contained in a weight mixing ratio of at least 10% and wherein said largest flexural rigidity is no greater than 10 times larger than the flexural rigidities possessed by the remaining filaments.

2. An improved synthetic textured yarn according to claim 1, wherein the relations among the total fineness (D of filaments having the largest fineness, the total number of said filaments (F and the total fineness of said textured yarn (D are defined by;

3. An improved synthetic textured yarn according to claim 2, wherein said filaments of the largest flexural rigidity and which are of largest fineness are provided with a circular cross sectional profile and said other filaments are provided with irregular cross sectional profiles.

4. An improved synthetic textured yarn according to claim 2, wherein said textured yarn is composed of a plurality of unit textured yarns and provided with an air content exceeding 5. An improved synthetic textured yarn according to claim 1, wherein the torsional rigidity of said filament having the largest flexural rigidity is more than 5 times the mean torsional rigidities of said other filaments.

6. An improved synthetic textured yarn according to claim 1, wherein the mean fineness of said all filaments ranges between 2.5 and 3.5 and the fineness of said filaments having the largest flexural rigidity is from 2 to 5 denier larger than that of said other filaments.

References Cited UNITED STATES PATENTS 3,199,281 8/1965 Maerov et al. 57--14O 3,396,529 8/1968 Stutz 57--140 3,438,190 4/ 1969 Collingwood 57-140 JOHN PETRAKES, Primary Examiner US. Cl. X.R. 57-157 

